In general, a hot-water heater, which heats air by using waste heat of engine cooling water, is used as a main heat source for heating an automobile interior. However, because of facts such as that the temperature of the engine cooling water is low at engine start, an electric heater is also provided as an auxiliary heat source. Further, it seems that, in the future, more electric heaters will be installed as electric vehicles will become widespread.
A PTC element is often used as a heating body in an electric heater (e.g., Patent Literature 1). A PTC heater disclosed in Patent Literature 1 has a structure including two heater units stacked on each other. In each of the heater units, fins are disposed above and below a PTC element, and electrode members are provided in contact with the fins.    [Patent Literature 1] Japanese Patent Application Publication No. H5-169967